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By Fred H. Lightner

Mergers and acquisitions (M&A) within the mining industry are becoming frequent events. Large companies and small companies alike are jumping on the bandwagon of merger mania. The results of these mergers have significant impacts on the employees of the involved companies. Comments, observations, and specific examples of the 'peop1e"aspect of mergers are presented in an attempt to answer the question "will it be business as usual?" My answer is a simple NO. This paper attempts to provide support for my conclusion. The reader should recognize that the comments, observations, and specific examples mentioned in this paper are subjective and reflect the experience and prejudice of the author.

Jan 1, 2001

By Jozef Szymanski, Julian Partyka, Jerzy Krynicki

In order to study blast-induced dust in a hard rock metal mine experimentally and analytically, a part of a stope mined by Vertical Retreat Mining (VRM) was monitored throughout its lifetime. Dust measurements were used to describe the dust source, to study the dynamics of removal of airborne dust from the blasting area, and to examine a variation in dust production with a stope's progress. An analysis based on graphical and analytical comparisons of blasts taking place in a single stope is presented and discussed. Also, some transient phenomena of dust flow in the stope vicinity, caused by the blasts only, are examined.

Jan 1, 1997

By D. C. Yang, J. Ye

A comprehensive flotation study has been conducted on a Chinese fluorspar ore using the packed flotation column developed at Michigan Technological University (MTU). The results are compared with those for a conventional mechanical flotation method on the same feedstocks. Key factors controlling flotation performance of both methods are evaluated based upon a simple statistic design. The flotation concentrate produced in one stage of the packed column has 4% to 5% higher recovery and much lower silica impurity than the concentrate produced by up to six stages using a conventional mechanical cell. The results also show that the packed-column flotation process is particularly suitable for the recovery of finer fluorspar particles.

Jan 1, 1993

By J. C. Willett, J. R. Sanfilipo, S. M. Podwysocki, P. D. Warwick

The U.S. Geological Survey is concluding an assessment of the major coal regions of the country. In this program, the quantity and quality of coals that are expected to be mined during the next 30 years are characterized. For the Gulf Coast region, the evaluation includes reviews of the stratigraphic setting, coal resources, and the quality of the Cretaceous to Eocene coals in four coal-producing areas. The coal-bed methane potential for these areas will also be evaluated. The results of these efforts will be a series of digital maps, text, and tables that will be published in a CD-ROM format.

Jan 1, 2000

By T. A. Toney, L. R. Fish, P. J. Bethell

With new lightweight designs, spirals have become standard equipment in coal preparation plants worldwide. To their credit, spirals typically show very low coal losses to the refuse stream under most operating conditions. However, spirals do tend to separate at cut points in excess of 1.80 S.G. Attempts to obtain lower cut points have typically resulted in coal losses to middlings. Middlings retreatment with secondary spirals is therefore becoming common place. Other forms of retreatment with water-only cyclones, hydrosizers and recirculation have been attempted with some success. This paper reports on a novel (patent applied for) approach to retreating spiral middlings in a heavymedia cyclone circuit.

Jan 1, 2000

By W. Douglas Gould, Mei-Lin K. Stichbury, Jeffrey G. Bain, Blowes David W.

The mechanisms of release of arsenic in gold mine tailings were investigated. The highest concentration of dissolved As (75 mg/L) was observed near the base of the tailings impoundment, in close association with a peat layer. Elevated concentrations of reduced iron and hydrogen sulfide were also measured at the base of the impoundment. High numbers of iron-reducing and sulfate-reducing bacteria were detected at depths within the impoundment which correlated with dissolved As, Fe and H2S. The data presented in this paper suggest that arsenic is released from the tailings by bacterially-mediated reductive dissolution of As-bearing iron minerals.

Jan 1, 2000

By Lynn B. Hales, John A. Herbst, Thomas L. Gabardi

A system for a continuous determination of the charge volume of grinding media in ball mills and SAG mills has been developed. The system, comprised of a unique measurement device and a model based Kalman filter algorithm, determines grinding media level within a mill and calculates media and liner wear rates. The signal from an instrumented washer mounted on the exterior of the mill shell is used to provide the measurement that, along with mill power and on-line models for media mechanics, result in estimates of mill parameters that can be used in media addition control strategies. Data are presented for a 12.5 x 15 ft. ball mill.

Jan 1, 1990

By James A. Morrison, Stephane Carayol, Paul H. Madsen

The Rio Piedras Alignment Section 7 of the Tren Urbano is currently being constructed beneath a historic commercial section of San Juan. Different portions of the section are being constructed using open cut, cut-and-cover, New Austrian Tunneling Method (NATM), Earth Pressure Balance Machine (EPBM), and as tacked drift mined support system. The combination of complex geology, low ground cover, and several innovative construction methods present many challenges to the ground control program. Mining and construction sequences were first developed to minimize ground movements and risk of damage to structures. A unique compensation-grouting program was developed to improve the ground, limit settlement, and recover settlements incurred due to mining.

Jan 1, 1999

By T. Gouri Charan, G. V. Rao

A spherical agglomeration process for the separation of scheelite fines of less than 30 µm in very low concentration of 0.04% WO3 in a binary mixture with quartz fines of less than 30 pm has been described. A concentrate containing 14% WO, with more than 90% recoveries could be achieved by means of anionic sodium sulfo succinate collector at pH 3.5 and also with commonly used anionic sodium oleate at pH 10.5 as per the conceptual flowsheet suggested. Such a process is envisaged as commercial potential for the recovery of fine-grained scheelite present in the tailings of gold plants as found in India.

Jan 1, 1991

By C. K. Nworu, L. O. Asuquo, C. O. Nebo

Selective flocculation studies of Agbaja iron ore with starch-type and nonionic polyacrylamide-type flocculants has been conducted to determine the effect of flocculant type. The results indicate that corn starch was slightly better than cassava starch in selectivity performance. Cassava starch was in turn better than Superfloc 16, while the poorest results were obtained with commercial starch. Sodium humate shows better dispersive capability, and thus enhanced flocculation results, than sodium silicate. Pulp pH affects the zeta potential, polymer chain configuration and hence selective flocculation. Overall results indicate that recovery and separation of this very fine grained iron oxide by selective flocculation is feasible.

Jan 1, 1995

By Dean J. Soderstrom

Soil and sands were contaminated with depleted uranium from weapons testing. This resulted in the formation of a complex mixture of uranium compounds. Characterization studies of the soil indicated the uranium was present as uranium metal, uranium oxides, silicon-bearing metallic uranium, and uranium silicates. A process was developed to selectively remove dense uranium compounds using gravity separation and a chemical extraction system to remove uranium which was not available for separation by gravity methods. Results from characterization studies and pilot scale testing are presented for background information. The primary purpose of this presentation is the report of the results achieved in the field application of the processes.

Jan 1, 1995

By J. B. Hiskey, V. P. Atluri

Resin-in-leach (RIL) cyanidation experiments were performed on a refractory carbonaceous gold ore. The objective of this investigation was to determine if strong-base ion exchange resins could adsorb the soluble aurocyanide complex in preference to natural "preg robbing" organic constituents. Direct cyanidation of the carbonaceous gold ore used in this study resulted in less than 2% gold extraction in 24 hr. RIL cyanidation resulted in about 70% gold recovery onto the resin. Kinetic experiments indicated that 50% of the gold is extracted after 1 hr of leaching. Resin breakage was investigated for as-received and preattrited resins. Similar results were obtained with three different strong base resins.

Jan 1, 1990

By David D. Gallagher, Edmond J. O’Donovan

It has been well accepted for many decades that hard starting of conveyors has associated problems. It is particularity damaging to the belt and splices. Recent measurements of hard starts on a long conveyor with a low modulus belt showed very unusual responses. These included violent accelerations and repeated "whip cracking" of the belt. Laboratory investigations of the very high strain rates experienced by the belt during the whip cracking, show mechanisms for belt damage that are not associated with normal usage. This paper outlines the measurement to show that for long, low modulus conveyors, constant torque controls are inappropriate and time ramp controls are really essential.

Jan 1, 1998

By Harold D. Taylor

Cone fitting is a procedure which can be used to estimate the short range, linear portion of a variogram. Rather than combining data over windows In different directions and fitting by hand, cone fitting estimates the variogram in all directions at once using a multiple regression approach. The method automatically provides estimates of nugget effect, anisotropy, and initial slope of the variogram. This paper presents the results of simulation studies which have been carried out. These studies Indicate that the method works well and that it may be particularly useful for small data sets. The simulation studies also indicate that the local variogram may differ greatly from the theoretical variogram.

Jan 1, 1986

By C. Roldan, C. Garcia, J. D. Miller, C. L. Lin

The ultimate recovery in a heap leaching operation is related to the degree of exposure of the valuable minerals in comminuted particles. Recently, high-resolution cone beam x-ray microtomography (XMT) has been used to determine this parameter. XMT technology consists of examining the extent of mineral exposure for each size fraction of ore in 3D, then, by algebraic calculations, the ultimate recovery can be estimated for different particle size distributions (PSD). To confirm the usefulness of the XMT technology for mineral exposure analysis, column tests were performed to determine ultimate recovery using three PSDs for two composites obtained from the copper heap leaching operation at Zaldivar-Chile.

Jan 1, 2003

By Lawrence J. Connelly

During the last decade, use of freeze conditioning agents (FCA) to ease unloading and handling of both run-of-mine and washed coal during periods of cold weather has become an accepted practice by the coal industry. This paper reviews some of the mechanical means of easing the handling of coal during periods of cold weather, as well as their use in conjunction with FCA's. Factors required to promote a successful cold weather handling program are also covered. Mechanisms by which FCA's function and the influence of various substrate characteristics on the ultimate response to freeze conditioning agent performance are discussed. A modified approach to freeze conditioning is presented.

Jan 1, 1986

By R. R. Rollins

Field data combined with theoretical derivations were used to design a surface mining operation using explosive casting. Calculated casting results varied from 44% to 65% depending on bench height. The field tests were performed at an Eastern, contour, coal stripping operation. Results from five experimental casting shots, using a shovel and trucks, are summarized and compared to conventional mining methods. The overburden material removed by casting ranged from 35% to 65%, with an average of 50%. Fragmentation was improved, and it was demonstrated that this procedure is economically attractive, with a resultant cost savings of $0.59/m3 or $5.93/t of clean coal.

Jan 1, 1988

By Karl H. Gehring

According to the increasing importance of boom type roadheaders in tunnelling essential problems occuring in the application of these machines are dealt with. Based on a chart including the various stages for decicion finding the excavation method of underground cavities, both the technical limits and economic criteria are discussed in order to determine the range of applicability of roadheaders. Giving examples-the numerous developments in the fields of pick and cutting technology, performance data of boom type roadheaders in hard rock, safety technology and increase in the machines' degree of utilization, research and development of VA is illustrated. Two topic operation examples show partial aspects of the various tendencies of development.

Jan 1, 1981

By Scott K. Palm

The initial intent of the Hazard Communication Standard (HCS) was to improve worker health by providing more information about the hazards of chemicals used in the workplace. However, the impact of the HCS goes well beyond worker right-to-know. There are direct costs associated with compliance. In addition, labelling and hazard communications can provide a competitive advantage to producers of minerals that have not been identified as hazardous. Often, the lack of hazardous information about a substance is due to the lack of scientific study, rather than an indication of product safety. Currently, industry and regulators sometimes give known hazards greater weight than unknown risks.

Jan 1, 1991

By Sharon G. Roness

Powder River Basin (PRB) mines were originally built to serve power plants designed specifically for their: coal. Sulfur was the major concern. Btu content and sodium limited the market for some plants. The PRB market has now extended to plants that are converting from other coals because of the Clean Air Act. These new customers are more sensitive to constituents that affect boiler and precipitator performance. At the same time, the prospect of deregulation is forcing power companies to improve cost controls. Kerr-McGee Coal's Jacobs Ranch Mine has responded to the changing marketplace with an expanded coal quality and customer service program.

Jan 1, 1998